Arrangement for stabilizing the gain bandwidth product

• Main Authors: MASTROCOLA; ANGELO ROCCO, PRATT; RANDALL RUSSELL, KHOURY; JOHN MICHAEL
• Format: Patent
• Language: English
• Published: 15.06.1999
• Edition: 6
• Subjects: AMPLIFIERS; BASIC ELECTRONIC CIRCUITRY; ELECTRICITY

A circuit for stabilizing the gain-bandwidth product of analog circuits containing bipolar devices which determine the gm is disclosed. The stabilization circuit is formed to generate a reference current that is proportional to a reference capacitance CS and the thermal voltage VT. The reference current is ultimately mirrored (as the bias current) into the bipolar devices which determine the gm within the analog circuit. Since the transconductance gm of a bipolar device can be expressed as collector current, IC, divided by VT, the thermal voltage factor of the bias current itself will "cancel" the thermal voltage factor present in the transconductance. The effects related to the remaining variable, the capacitance, will be eliminated as long as the reference capacitance is formed to "track" the analog circuit capacitance by using similar types of capacitance to implement both capacitors and forming both the stabilization circuit and the analog circuit on the same silicon chip. The stabilization circuit can be constructed in modular form and may include a module capable of creating a stabilized RC time constant that is likewise unchanged by variations in temperature or processing.